the case of the utah doctor on trial for killing his wife. The testimony is over. The defense has rested. And the case could go to the jury as early as today. Abc's aditi roy has all the latest. Reporter: After more than a dozen days of prosecution TESTIMONY, martin MacNeill's defense team finally presented itself case to the jury. Did you have occasion to associate with my client, MR. martin MacNeill? Yes. Reporter: For more than two hours thursday, with four witnesses, including one of the defendant's former colleagues, MacNEILL'S ATTORNEYS BUILT A Time line, to show the utah physician's whereabouts on the day his wife died. We had two interactions that day. The first one was as he was leaving to pick up his kindergartner from her morning kindergarten, about a block or two away from the developmental center. Reporter: Prosecutors say MacNEILL KILLED HIS WIFE, Michele, by giving her a deadly dose of painkillers and putting her in a tub while she was recovering from plastic surgery. MacNEILL SAYS HE IS INNOCENT. The state says his motive was to continue an affair with gypsy willis. You continued holding yourself out as husband and wife? I believe so. Reporter: Did you get a marriage license? We did get a marriage lines license. We didn't actually get married, though. Reporter: Willis, reading jailhouse love letters she RECEIVED from MacNeill, when they were incakacarcerated fraud case. I want to be as good as I can be when I get out of here so you will still feel the same about me. I love you and miss you more than you can imagine. Was that reciprocated by you? At the time, I had lost most of my friends and all of my family. I wanted to be in contact with anyone I could be, yes. Reporter: Willis testified the two are no longer together. With both sides resting and closing arguments today, the JURY WILL SOON decide MacNeill's fate. For "good morning america," aditi roy, abc news, los angeles. Let's bring in abc's chief legal affairs anchor, dan abrams. The defense, pretty short. And very simple. Yeah. They're making two, basic points. He might have had an alibi. They say he did have an alibi. And number two, this is an important point. He might not have been able to lift his wife out of the bathtub. Why is that so important? When he calls 911, I can't lift her out myself. He sends his daughter next door to get the neighbors. He specifically says I need a man's help to get her out of the tub. And prosecutors have alleged this was just his effort to delay getting help. That he wanted to make sure, in effect, that she died. The defense is trying to provide the jury with some ammo to come forward and say, maybe it's true that he couldn't have lifted her out of the tub alone. This is the sort of thing where jurors are going to apply common sense. Have an ergonomics expert say we hoisted this. This is the thing where jurors are going to say, if my blank was in the tub, would I be able to lift the person out by themselves? And I think that that's the PROBLEM martin MacNeill has here. Most people are going to look at this and say, if my wife or husband was dying, in my bathtub, I am sure I would be able to somehow move that person out of the tub in some way, shape or form. So, that's the difficulty he has. Closing arguments coming up now. Expect prosecution to focus on what the evidence does show. The defense will focus on what it doesn't show.

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